Calculation method and system for obtaining current-carrying capacity critical environment temperature of direct-current cable

Abstract

The invention discloses a calculation method and system for obtaining the critical environment temperature of the current-carrying capacity of a direct-current cable, and belongs to the technical field of power systems. The method comprises: acquiring direct-current cable insulation material parameters, performing function fitting on the direct-current cable insulation material parameters, and generating a conductivity numerical model; obtaining the equivalent conductivity of the DC cable insulation material, the intermediate point electric field value and the temperature value of the DC cableinsulation material insulation layer and the leakage current of the DC cable insulation material insulation layer according to the conductivity numerical model, and determining the electric field distribution of the DC cable insulation material insulation layer; when it is determined that the electric field in the insulating layer of the insulating material is maximum, the outer-layer temperatureand the maximum temperature gradient of the insulating material of the direct-current cable are obtained; and obtaining an environment temperature relational expression according to the maximum temperature gradient, and calculating the critical environment temperature of the direct current cable by combining a thermal circuit model between the current-carrying capacity and the wire core temperature. Under different environment temperatures, the maximum temperature gradient and the environment temperature critical value of the current-carrying capacity of the cable are controlled through the wire core temperature.

Description

Technical field [0001] The present invention relates to the technical field of power systems, and more specifically, to a calculation method and system for obtaining the critical ambient temperature of the current carrying capacity of a DC cable. Background technique [0002] Unlike AC cables, the conductivity of extruded DC cable insulation materials is affected by temperature, and the electric field distribution in the insulation layer will be reversed, so it cannot operate under a large temperature gradient. At present, the calculation of DC current-carrying capacity mainly adopts the finite element method, but this method needs to repeatedly set the initial current-carrying capacity value. The efficiency is very low, and the limitation of the highest electric field in the insulating layer and the influence of ambient temperature on the temperature gradient are not considered Can put forward the judgment method of the current-carrying capacity of the cable under the low-temper...

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Problems solved by technology

[0002] Unlike AC cables, the conductivity of extruded DC cable insulation is temperature-dependent, and the electric field distribution in the insulation is reversed, so it cannot operate under large temperature gradients

At present, the calculation of DC current carrying capacity is mainly calculated by finite element method, but this method needs to repeatedly set the initial current carrying capacity value, the efficiency is very low, and the limitation of the maximum electric field in the insulating layer and the influence of the ambient temperature on the temperature gradient are not considered. It can propose the discrimination method of cable ampacity control at low temperature, but cannot provide reference for the control of DC cable ampacity in operation

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